The present invention relates to a screwdriver bit and, more particularly, to a screwdriver bit releasably coupled with a screwdriver for driving screws or the like.
Screwdriver bits releasably coupled with a screwdriver for driving screws or the like are well known and have various types such as rectilinear, cruciform, hexagonal, inner hexagonal, and ring shapes corresponding to various groove shapes in the screw heads.
FIG. 1 of the drawings illustrates a typical screwdriver bit 12 including a shank 121 releasably coupled with a socket 13. The bit 12 further includes an end 122 having an insertion portion 123 with a shape corresponding to that of a groove 21 in a head of a screw 2. The socket 13 is attached to a head 111 on an end of a handle 11 of a wrench 1 or a power tool (not shown). Releasable coupling between the bit 12 and the socket 13 allows a user to select a proper bit according to the type and size of the groove of the screw to be tightened or loosened.
In some bits, the cross sectional area of the insertion portion 123 is smaller than that of the shank 121 whose size is fixed for coupling with the socket 13. Stress concentration exists in a transition section 125 between a root section 124 of the end 122 of the bit 12. Breakage of the bit 12 in the transition section 125 may occur during operation, resulting in potential a hazard to the user.
It is, therefore, a need for a screwdriver bit with enhanced safety during use.